Theory Of Operation

The A/C Pressure Sensor monitors the pressures in the high side of the A/C refrigerant system through its connection to a fitting on the A/C discharge line and its internal resistance changes in response to the pressures it monitors. The Powertrain Control Module (PCM) provides a 5-Volt reference signal and a sensor ground to the A/C Pressure Sensor, then monitors the output voltage of the transducer on a sensor return circuit to determine refrigerant pressure. The PCM is programmed to respond to this and other sensor inputs to control the operation of the A/C Clutch and the Radiator Cooling Fan to help optimize A/C system performance and to protect the A/C system components from damage. The PCM will request disengagement of the A/C Clutch when the refrigerant pressure rises above 3219 kPa (476 psi) and re-engage the clutch when the pressure returns below 2937 kPa (426 psi). The PCM will also disengage the A/C Clutch if the refrigerant pressure drops below 110 kPa (16 psi) and will re-engage the clutch when the pressure returns above 220 kPa (32 psi). When the refrigerant pressure rises above 1655 kPa (240 psi), the PCM will actuate the cooling fan.